NASA didn’t just send people to the Moon to jump around and hit golf balls. During their brief time on the lunar surface, Neil Armstrong and Buzz Aldrin, two Apollo 11 astronauts, conducted science experiments.
Scientific Experiments by Apollo 11
The Apollo 11 crew performed many experiments on the lunar surface.
The results were either radioed back to Earth by the crew or returned to Earth for laboratory analysis.
Neil A. Armstrong and Edwin E. “Buzz” Aldrin, Jr., Apollo 11, set up two scientific experiments near their landing site in the Sea of Tranquility.
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The Early Apollo Scientific Experiment Package.
Lunar Laser Retroreflector
1. A Laser Ranging Retroreflector – Measured the distance between the Earth and Moon precisely.
The space race produced an internal science race to decide what experiments would be on board the Apollo 11 first mission to land humans on another world.
The winner was a device that enabled scientists to measure the distance between the Earth and its satellite with unprecedented precision.
This experiment was crucial in general testing relativity and understanding the Moon’s complex wobbles as it spins on its axis. It was also astonishingly easy compared with the immense complexity of the overall mission.
James Faller, 1963, joined the (JILA) Joint Institute for Laboratory Astrophysics of the National Bureau of Standards and University of Colorado, Boulder.
As a graduate student at the prestigious Princeton University, he had drafted an article titled: “- A Proposed Lunar Package: A Corner Reflector on the Moon,” envisioning a robust and lightweight reflector measuring barely two to three pounds that would be deployed on the lunar surface.
A Light Beam From Earth
Later a light beam from Earth would be targeted at the reflector. The instrument would then detect the laser and reflect the light to Earth.
The period it took for the light to get the round trip from the Earth to the Moon and back would “permit a precise earth-moon distance measurement to be made.”
Shorter than a decade later, the world would understand how insightful Faller’s project had been.
Accompanying JILA colleagues Peter Bender and Jan Hall, he organized a lunar ranging team to investigate the feasibility of placing a retroreflector on the lunar surface.
A corner cube retroreflector offered an ideal design. It consisted of three mirrors set precisely at right angles to each other, like the inside corner of a cardboard box.
That design makes the incoming light bounce off three surfaces, and the laws of optics ensure that it will always bounce straight back to the source. The Lunar Laser Retroreflector experiment was wildly successful.
The Lunar Laser Retroreflector experiments remain some of the most important scientific achievements of the Apollo missions.
They are adding to our knowledge of everything, from general relativity to the inner structure of our Moon. Furthermore, the first reflector remains the only equipment still working at the Apollo 11 landing site.
Passive Seismic Experiment
2. Passive Seismic Experiment – detected lunar “moonquakes” and provided information about the Moon’s internal structure.
The picture above shows Apollo 11 Astronaut and Lunar Module pilot Buzz Aldrin during the extravehicular activity on the Moon.
Buzz had just deployed the Early Apollo 11 Scientific Experiments Package.
Beyond it is LR-3 or the Laser Ranging Retro-Reflector. In the foreground is the Passive Seismic Experiment Package.
Apollo 11 Solar Wind Composition Experiment
3. Solar Wind Composition Experiment – Collected samples of the solar wind for analysis on Earth.
Our Sun continually emits a flux of electrically charged particles into space. This is called the solar wind.
The Earth’s magnetic field stops these charged particles from striking the Earth’s surface. Although in the Earth’s polar regions, particles can reach the upper part of the atmosphere, creating the famous auroras.
Because the Moon is outside the Earth’s magnetic field for most of each month and has no atmosphere, it allows the solar-wind particles to reach the lunar surface.
The Solar Wind Composition Experiment was conducted on the Apollo 11, 12, 14, 15, and 16 missions.
It was made of an aluminum foil sheet, 0.3 meters by 1.4 meters. It was positioned on a pole fronting the Sun.
A platinum sheet was also used on the Apollo 16 mission. This foil was exposed to the Sun for periods varying from 77 minutes on Apollo 11 to 45 hours on Apollo 16, enabling solar wind particles to embed themselves into the foil.
Variety in the Composition of the Solar Wind
The foil was later returned to Earth for laboratory analysis. It allowed the chemical structure of the embedded solar wind to be defined more accurately than would be achievable if the measurements were made using remotely controlled devices on the Moon but limited the periods at which observations could be made.
The light noble gases of the isotopes were measured, including helium-3, helium-4, neon-20, neon-21, neon-22, and argon-36.
Some variety in the solar wind composition was observed in the analyses from the various missions.
These differences were correlated with variations in the intensity of the solar wind, as discovered from magnetic field measurements.
The Soil Mechanics Investigation
4. The Soil Mechanics Investigation – Studied the lunar soil’s properties and collected geologic samples.
And the use of penetrometers, which are small poles that measure the force required to penetrate various depths in the ground. Furthermore, several small trenches were dug.
Soil mechanics is the art of the mechanical properties of soils and the way that these features affect human activities.
Soil mechanics investigations were performed on all six of the Apollo lunar landings.
The purposes of these studies were both to increase our scientific understanding of lunar soil’s properties and present the engineering knowledge required to plan and perform Moon surface activities.
Moon’s Soil Mechanics
Soil mechanics studies took a mixture of forms. These incorporated crew commentary while handling geologic samples and deploying experiments and post-mission analysis of photography of these projects.
Many experiments were conducted specifically to study soil mechanics. These involve using penetrometers, which are rods that measure the force needed to penetrate various depths in the soil.
Furthermore, many small trenches were dug to study the soil characteristics along the trench walls.
Lastly, studies were conducted on samples returned to Earth. For instance, the analysis of core tubes allows properties such as density, strength, compressibility, and average grain size to be measured as a function of the depth.
The Lunar Surface is Fine-Grained
When landing, the impact of rocket exhaust on the surface created dust clouds.
On some Apollo missions, dust became evident 30 to 50 meters above the surface, and through the final ten to twenty meters of descent, the character was mostly obscured by the dust cloud.
On other Apollo Moon missions, the dust cloud was not as dense, and the surface remained visible during the landing.
The soil on the lunar surface is relatively fine-grained, with more than half of all grains being dust particles less than 0.1 millimeters crosswise.
Some of these particles are electrostatically charged and stick to objects (such as equipment and spacesuits) that the astronauts touch.
The dark lunar dust grains absorb sunlight, and the equipment that became dust-coated sometimes became very hot.
The Astronauts Boots Only Penetrated 1 to 2 Centimeters
Despite the fine-grained lunar surface, it provided excellent traction for astronauts as they moved about.
Both in the Lunar Rover and on foot, Crew mobility was affected more by local topography, such as ridges and craters, than by soil properties.
The Moon’s surface efficiently carried the astronauts’ weight and gear.
Typically, Lunar Rover’s wheels and astronaut boots only penetrated 1 to 2 centimeters into the lunar surface, with penetration approaching five centimeters in some places.
The Lunar Module Footpads Settled 2 to 20 Centimeters
The LM or the Lunar Module footpads settled 2 to 20 centimeters into the Moon’s soil.
When Apollo astronauts implanted sampling tubes into the lunar soil, they typically discovered penetration was relatively easy for the first ten to twenty centimeters and more difficult below that depth.
The most penetrating achieved on a hand-driven core tube was 70 centimeters, which needed around 50 blows with a hammer.
The astronauts on Apollo missions 15, 16, and 17 used a battery-powered drill to sample at greater depths.
This enabled sampling to depths of 1.5 to 3 meters, which was done quickly on Apollo 16 but with much more hassle on Apollo 15 and 17.
Apollo 14 astronauts deployed the Apollo Lunar Surface Experiments Package’s power source (foreground) and “Central Station” (background), where the Lunar Dust Detector was mounted. Credit: NASA & JSC.
The Lunar Dust Detector
5. The Lunar Dust Detector – Studied the effects of lunar dust on the operation of the experiment package.
This group of experiments was, as mentioned before, called the Early Apollo Scientific Experiment Package.
It was less comprehensive than the experiments conducted on the following missions.
This was due to time restrictions on the EVA and the Apollo 11 payload mass constraints.
Before the Apollo landings, everyone thought that a thick dust layer would accumulate on the experiment packages during the LM’s or the Lunar Module’s ascent and perhaps from other long-term sources.
The lunar dust detector was designed to measure the lunar dust layer deposition, and it was performed on Apollo missions 11, 12, 14, and 15.
Apollo 11 The Lunar Dust Detector
On Apollo 11, the lunar dust detector was connected to the Passive Seismic Experiment and estimated the power output from a collection of solar cells.
The dust buildup was significantly lower than expected. The conclusions from this experiment were also used to monitor the long-term degeneration of solar cells from radiation and thermal effects.
All of this was considered to be an engineering rather than a scientific experiment.
Apollo 11 Dataset Descriptions
The National Space Science Data Center (NSSDC) collects information and data on all Apollo experiments upon request from organizations or individuals in the United States.
The same services are open to scientists outside the United States through the World Data Center A for Rockets and Satellites.
Catalog of Apollo Experiment Operations
This Johnson Space Center site archives each experiment and equipment item deployed or operated on the lunar surface during the Apollo program.
It compiles some of the general problems encountered with these experiments and provides guidelines for the design of later lunar surface experiments.
What have we learned from Apollo 11 Experiments?
The scientific results and examples from Neil Armstrong and Buzz Aldrin’s 21-hour and 36-minute visit to the Moon provided invaluable data and fueled research long after the mission was over.
After the LM, or the Lunar Module, landed on the lunar Sea of Tranquility, Neil and Buzz handled a series of landmark scientific experiments.
Buzz deployed the EASEP, Early Apollo Scientific Experiments Package, which carried instruments for various tests to be left on the lunar surface.
The Apollo 11 team also recorded comprehensive observations of the Moon’s surface, photographed each other and the terrain, and gathered 22 kilograms of rock, dust samples, and soil in about two hours.
Still, though the mission was completed 51 years ago, amazingly, it’s bearing fruit.
What Apollo 11 taught us gave us a far better understanding of the solar system’s origins.
Lasting Legacy From Apollo 11 Experiments
The measurements and material gathered by the Apollo 11 crew led to discoveries.
Among the most important findings was that analysis of the chemical structure of lunar rocks helped strengthen the theory that the Moon was a chip off the young Earth.
The Origin of the Moon
Researchers now believe that soon after the solar system’s creation, Earth was struck by a Mars-sized object, intimately merging the two bodies.
Some of the resulting gas and rock later hardened into the single satellite that is our Moon now.
This origin story describes why the Moon doesn’t have a massive iron core and is mainly composed of materials located in Earth’s crust. It also explains why the ratios of many isotopes on the Moon’s surface are identical to those found in rocks on Earth.
That’s it. I hope you enjoyed this essay. Check out this article, which reveals the inside of the Apollo Saturn V rocket and its significant components. See for yourself these fantastic drawings. You will be amazed.
The space agency is now working, via its Artemis program, to land two astronauts close to the Moon’s south pole, hopefully in 2025. By 2028, it will establish a long-term, sustainable presence on and around the Moon.
